Re: [PLUG] Solaris backup/restore

[Rich Freeman <r-plug@thefreemanclan.net>]

On Wed, Feb 6, 2013 at 12:14 PM, Eric Lucas <eric@lucii.org> wrote:
> I'm preparing a proposal to set up and document backup/restore procedures
> for a series of Linux computers and a Sun Solaris 10 computer.  They want to
> use Mondo Rescue for the Linux systems and I'll work that out... it's the
> Solaris box that I'm not sure about.
>
> Their backup requirement is very specific - they simply want to be able to
> drop in two new HDs (RAID mirror), boot from a DVD, and then restore the
> entire system exactly as it was.  The restore needs to be entirely from
> DVDs.  They suggested using dd and scripting it but I know the disks (200
> GB) are not full so using dd seems like a crazy waste of space (DVDs full of
> nothing.)
>
> I'm not familiar with Solaris - anybody know what they have to perform this
> type of operation?

I know little of Solaris (beyond the pain I went through to get Gentoo
prefix working on it), but are you saying that the backup strategy is
to just image the hard drives onto new ones, such that you could just
swap them out to restore them?  That is of course wasteful of space
and necessitates a full backup each time unless you overwrite the
media, but it obviously makes recovery simple.

If so, then you might look at clonezilla.  It can be run from a boot
CD and I think you can fully script it (ie plug in the disks and boot
it from CD and it just runs).  Normally you'd use it to store the data
on image files on some server (samba, ssh, etc - it is pretty
versatile).  however, I believe it can also just be used to create
disk images.

Its main advantage (beyond the GUIs/etc) is that it uses a bunch of
individually-simple tools, and it is filesystem-aware.  The backups
themselves are image files (unlike tarballs) so they create
bit-identical images of what they copy.  However, clonezilla can
detect certain partition types and interpret the free-space data,
skipping backups of any blocks that are unused.  That obviously saves
a heap of time/space (not that you'd benefit from the space part).
Since it is only interpreting free-space use but otherwise storing
dumb images you don't have as much risk that it doesn't implement some
filesystem feature and corrupts your data (assuming it doesn't miss an
in-use block).

For filesystems it does not recognize it is the equivalent of dd.  I
don't know offhand if your filesystems will fall into this category or
not.

If you don't want to do disk images a tool I use is dar, which is
similar to tar, but it is optimized more for disk-based storage (where
seeks are inexpensive).  Most notably it stores an index at the end
which means that to restore one file you don't have to read through
the entire file.  It also handles incremental backups.  I use a script
called sarab to automate it - basically it just automates dar and
allows it to use a rotation schedule.  The schedule can be whatever
you want it to be, but in my case to do a full restore I'd need to
restore a bimonthly full backup, every weekly backup since then, and
every daily backup since the last weekly backup.  I could just as
easily only require one weekly backup and one daily backup, or just do
a full backup daily.

If you intend to only have one set of backup media I'm not aware of
any tools that could be used to incrementally update an image (that is
detect only modified blocks and copy those without a full compare).
You couldn't do any kind of incremental backups without overwriting
media in-place, since only storing modified blocks would not result in
a directly-usable disk image.

Hopefully some of this has been useful.

A more practical strategy would be to use a central server to store
backup files of individual systems and store them as image files.
This would use far less space, though to restore a system you'd have
to copy the data back over the network which would involve more
downtime.  Clonezilla can be used in this manner, and that is how I
backup my smaller home PCs (mainly for recovery convenience - they do
not store non-reproducible data so I only back them up monthly).

Rich
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